1. Field of the Invention
The present invention relates to an ink set for ink jet recording used in high-speed ink jet printers, an ink jet recording method and an ink jet recording apparatus.
2. Description of the Related Art
So-called ink jet system printers which record images by ejecting liquid or molten solid inks from nozzles, slits, or porous films onto paper, cloth, or a film are widely used, since they have many advantages such as compactness, moderate price, and silent operation, in particular since they allow full color printing by ejecting 3 or 4 colors simultaneously.
Recently, ink jet printers have increasingly achieved higher image quality and speed. However, a balance between the drying characteristics of inks and image quality is essential for high-speed printing. Usually, the permeability of inks is increased for improving the drying characteristics thereof, but this method also causes decrease in optical density and in character quality at the same time. This balance is particularly important for black inks, which are used to print characters.
Although divided printing using a longer printing head is one method for accommodating high-speed printing, division does not provide sufficiently high printing speed. Another method for this purpose is the use of reactions between inks. For example, a method of printing images by using a black ink suitably improved in drying characteristics and reactive color inks at the same time is disclosed. Although a balance between the drying characteristics of inks and optical density and character quality is established to some degree by this method, sufficient drying characteristics have not yet been obtained (e.g., see Japanese Patent Application Laid-Open (JP-A) No. 2001-152063).
Further, another method of printing images using a black ink improved in drying characteristics and reactive color inks at the same time is disclosed. The method is compatible with high-speed printing, has superior ink-drying characteristics and allows high optical density, but does not provide sufficient character quality. Accordingly, there exists a need for inks having favorable drying characteristics, high optical density, and excellent character quality compatible with high-speed printing (e.g., see JP-A No. 2001-294788).
Therefore, there is a demand for an ink set for ink jet recording compatible with high-speed ink jet printers that dries rapidly and provides images higher in optical density and printing evenness in full color printing, and an ink jet recording method and an ink jet recording apparatus that allow rapid drying of the inks and printing of images higher in optical density and excellent in character quality.